DIR- GUE CCR Fundamentals

[Nick_Radov]

My rumor mill spins in the direction of the curriculum refactor only including the JJ; I.e., no changes to GUE approved units at this time.

This is confirmed. The latest round of GUE standards changes doesn't include approval of any other CCR models. The JJ-CCR remains the only approved option. (They do still have the PSCR course listed if someone wants to learn the Halcyon RB80.)

 

[Matan]

So, most of the details of CCR Fundamentals seem to be out, but there's still some unclear pieces:
- 30m max, MDL dives only (although - is that OC MDL or CC MDL? You could do a much longer dive @ 24m or 21m with a CCR than on 32)
- Approved gases - GUE site says "Standard gas mixes in Fundamentals, helium introduced in Tech 1." But the current CCR standard DIL chart shows a MOD of 15m for 32%, and 21/35 is the approved DIL for 15-30m dives.

1. MDL is MDL - if you do a 30m dive the MDL is exactly the same.
it's true that due to constant PPO2 in CCR once you go shallower you'll get "more" bottom time (more than the OC), but that's the not the case the standards refer to - their point is no deco.

2. Helium is better to reduce gas density regardless of narcosis - this is true in OC as well - but in CCR it's more "economic" ^^.


Matan.

 

[justinthedeeps]

1. MDL is MDL - if you do a 30m dive the MDL is exactly the same.

Might work out that way for 30 metre bottom times on air diluent vs. OC on EAN32, as loop mix will also be ~32% nitrox @1.3 setpoint

BUT you could dramatically extend shallower phases coming up from a 30 metre dive, staying at 24m or 21m much longer on a CCR without ever reaching NDL/MDL or doing any gas switches, which is what @ChrisMBC might be saying. You'd need to be on an OC gas of ~38-42% EAN to get a similar NDL / MDL there, or keep diving for an hour or two longer on a stage or two of 50% @21m

The math also seems tricker at 30 metres on a 21/35 diluent vs a 21/35 OC gas: a ~32/30 loop mix @1.3 setpoint (preserving N2/He proportions displaced by increased oxygen) sounds better there than 21/35. At 40 metres it might be a ~26/33 loop mix, also still better (?)

But I guess just abiding by a simple OC N/MDL ruleset is simple enough if you're trying to stay matched with OC-compatible standards.

 

[Nick_Radov]

The embargo is lifted so the InDepth magazine article CCR Fundamentals has been published.

Introducing GUE’s new CCR Fundamentals Course

By Graham Blackmore Closed Circuit Rebreather (CCR) Fundamentals is here – It is a CCR class you can do if you’re a Technical Fundamentals diver. Global Underwater Explorers (GUE) ran its first CCR classes in August, 2013, and this initial iteration required a Technical Diver Level 2 pass for...

indepthmag.com

 

[flymolo]

Might work out that way for 30 metre bottom times on air diluent vs. OC on EAN32, as loop mix will also be ~32% nitrox @1.3 setpoint

BUT you could dramatically extend shallower phases coming up from a 30 metre dive, staying at 24m or 21m much longer on a CCR without ever reaching NDL/MDL or doing any gas switches, which is what @ChrisMBC might be saying. You'd need to be on an OC gas of ~38-42% EAN to get a similar NDL / MDL there, or keep diving for an hour or two longer on a stage or two of 50% @21m

The math also seems tricker at 30 metres on a 21/35 diluent vs a 21/35 OC gas: a ~32/30 loop mix @1.3 setpoint (preserving N2/He proportions displaced by increased oxygen) sounds better there than 21/35. At 40 metres it might be a ~26/33 loop mix, also still better (?)

But I guess just abiding by a simple OC N/MDL ruleset is simple enough if you're trying to stay matched with OC-compatible standards.

I don't think GUE advocates for 1.3 on the bottom

 

[justinthedeeps]

We have decided to introduce “the small rig” where manifolded double 3L /23 cu ft diluent and a smaller oxygen bottle can be used instead of bigger configurations suitable for more advanced dives.

This sounds much nicer for divers' knees and discs

CCR-T1 will not be eligible to do OC dives within a Tech 1 range

Do all of the CCR-twinset drills not directly translate to the very same OC procedures? I thought the GUE CCR config/approach was designed that way?

 

[flymolo]

I don't think GUE advocates for 1.3 on the bottom

just to expand on that, gue ccr standard gasses target a dil po2 of 1.0 to make for efficient dil flushing and cell validation

 

[justinthedeeps]

I don't think GUE advocates for 1.3 on the bottom

Oh ok, I don't either--I prefer 1.1 or 1.2 myself!
But it seems like a lot of people are running 1.3 [setpoint, not dil ppO2] on ≤50 metre dives, and I've seen GUE CCR divers doing it.

I don't think that changes the air dil / EAN32 @30 metres situation much, nor what @ChrisMBC was saying.

For the 21/35 cases, at 1.2 [setpoint] we're looking at:
a ~30/31 loop mix at 30 metres (sounds nice)
a ~24/34 loop mix at 40 metres (also nice)

At 1.1 [setpoint]:
28/32 @ 30m (still good)
~22/35 @40m (not worse, but closer to equivalence)

 

[justinthedeeps]

just to expand on that, gue ccr standard gasses target a dil po2 of 1.0 to make for efficient dil flushing and cell validation

Certainly this also seems to be what 100-metre ('Mod3'), and perhaps even some 60-metre ('Mod2') divers are doing under other training regimes.

Is GUE CCR 1.0 even at 30 metres?

[Edit note--I was talking about setpoint for NDL/MDL purposes in previous posts, versus diluent ppO2 which is different]

 

[flymolo]

Certainly this also seems to be what 100-metre ('Mod3'), and perhaps even some 60-metre ('Mod2') divers are doing under other training regimes.

Is GUE CCR 1.0 even at 30 metres?

dil po2 1.0 yes but i believe target ppo2 is ~1.2 or lower, dependent on cns exposure tables